"His life has been spent in unremitting industry and with uncommon success; he was the first who manufactured iron in this county with success, and the present improved state of that manufacture is greatly indebted to him; he is now brought to the close of his labors, but as a useful member of society, his place will not soon be supplied."

Isaac Meason obituary, 1818.

Isaac Meason is known today primarily for his grand Georgian house that still stands in Fayette County. But as his obituary testifies, he was a great promoter of iron manufacturing. Meason started in the iron industry by constructing Union Furnace in 1791, along Dunbar Creek in Fayette County. This was one of the earliest furnaces built west of the Allegheny Mountains, along with Alliance Furnace, built about 1790. In 1793 he replaced this furnace with a second, larger one just downstream. Between 1795 and 1800 he built Mount Vernon Furnace, also in Fayette County.

By 1800, Meason had already accomplished much to establish iron manufacturing in western Pennsylvania.

Signature stone of the Meason House, Fayette County, PA.

He would make his most notable mark in the iron industry, hoever, by financing one of the nation's first rolling mills. In 1816 Thomas Lewis, a Welsh immigrant who had learned how to make and roll iron in Wales, came to Isaac Meason in Fayette County and convinced him to bankroll new iron works. With Meason's support, Lewis constructed a rolling mill at Plumsock, which included two puddling furnaces and trains of rolls, to make bar iron. Three other Lewis brothers from Wales were on hand when the mill rolled its first bar iron in 1817. The Lewis brothers and Meason demonstrated to Pennsylvania ironmasters that a rolling mill could successfully make iron products.

Trains of rolls in rolling mills were a major change in iron-manufacturing technology. Through the 1700s and early 1800s refinery forges, such as Charming Forge, had hammered pig iron from charcoal furnaces into various products, including bars, rod, sheet and plate. After 1800 some iron from refinery forges and charcoal furnaces also went to rolling mills, where pig iron from furnaces or bar iron or blooms from forges were reheated and passed back and forth between trains of rolls to shape plate, sheet, rod, bar or other iron products. The trains of rolls were a significant advance over earlier refinery forges because they could produce more plate, sheet or other products at lower cost.

Diagram of a typical puddling furnace.

Puddling furnaces were an important part of the technological advance that rolling mills represented. Puddling furnaces worked much differently from charcoal furnaces and refinery forges. Both charcoal furnaces and refinery forges kept the fuel and iron in direct contact with each other. Iron makers had to use charcoal, a form of carbon from which most impurities were removed, so that impurities from the fuel did not contaminate the iron and lower the iron quality unacceptably.

Even with charcoal as fuel, ironworkers sometimes struggled to make iron of sufficient quality. Unlike charcoal furnaces, puddling furnaces had two chambers, separated by a low wall. The fuel stayed in one chamber, the iron in the other chamber, and heat and gases streamed off the fuel, heating the iron. The separate chambers prevented the fuel from coming into direct contact with the iron and contaminating the iron with impurities.

Puddling thus enabled greater control over the purity and quality of the product, and allowed the use of less pure but cheaper fuels, such as anthracite or bituminous coal or coke. Puddling furnaces also eliminated the costly, time-consuming step of hammering iron in refinery forges before the iron went to rolling mills. Because iron could be taken directly from puddling furnaces to a series of rolls, puddling furnaces were often paired with rolling mills.

Lewis and Meason helped bring rolling-mill technology to Pennsylvania, which had developed previously in Britain. By 1850, Pennsylvania ironmasters had adopted rolling mills as a mainstay of the industry.

Meason did not live long enough to witness this spread, for he died in 1818, shortly after his rolling mill went into production. The Plumsock rolling mill later disappeared. Today, Meason's most visible legacy is his 1802 mansion, which the National Park Service designated a National Historic Landmark as one of the nation's best examples of Georgian architecture.